We propose to acquire a ADSC HF-1M Dual Mode Pixel Array Detector system to support the static and time-resolved fiber diffraction and macromolecular small-angle solution scattering (SAXS) experimental programs at the BioCAT Beamline 18ID at the Advanced Photon Source, Argonne National Laboratory. The BioCAT facility is a NIH supported Biotechnology Research Center (BTRC, 9 P41 GM103622-18) that undertakes the core, collaborative and service research required of such resources. A core group of major users of the proposed instrument has been selected from the Driving Biomedical Projects for the BioCAT BTRC that address a diverse array of biomedically important projects such as cardiac and striated muscle regulation, macromolecular folding and the structure of macromolecular complexes. A relatively stable group of NIH funded investigators comprising service users of the BioCAT facility are proposed as minor users of the proposed instrument. Access to BioCAT facilities, however, are open to everyone on the basis of peer-reviewed beamtime proposals so this list is expected to grow substantially in size and expand in scope with time. An important use of the detector will be in concert with core technology development programs within the BioCAT project that develop new instruments and techniques that can benefit all users of the facility. These include millisecond time resolution muscle diffraction and stopped flow SAXS experiments as well as <100 microsecond time resolution continuous flow SAXS experiments. The enabling technology provided by the proposed detector is the ability to provide 1k x 1k, 150 m pixel, 160 x 160 mm square frames at either 500 Hz (dual photon counting and integrating mode) or 1 kHz (photon counting) with only 1 micro-second between frames, providing a close to ideal match to the BioCAT time resolved solution SAXS and muscle diffraction programs. The improved signal to noise over existing detectors and faster frame rates will transform these experiments from being just possible to being practical and efficient to the benefit of the broad scientific community.